WAVE-PROPAGATION INTERACTION WITH FREE AND FLUID-LOADED PIEZOELECTRIC SUBSTRATES

A unified analytical treatment is presented that is supported with numerical illustrations of the interactions of ultrasonic waves with piezoelectric anisotropic half-space substrates. The solids are allowed to possess up to monoclinic anisotropic symmetry and associated piezoelectric coupling. The solids are also assumed to be loaded with water and subjected to incident acoustic beams at arbitrary polar and azimuthal angles. Simple analytical expressions for the reflection and transmission coefficients are derived from which all propagation characteristics are identified. Such expressions contain, as a by-product, the secular equation for the propagation of free harmonic waves on the piezoelectric substrate. It is found that piezoelectric coupling, as well as water, influence both types of modes. Higher symmetry, such as orthotropic, transverse isotropic, and cubic, are contained implicitly in this analysis. This paper also demonstrates that the motion of the surface and SH modes uncouple for propagation along axis of symmetry. For such cases, however, piezoelectric coupling can influence one of these types of modes depending upon the type of piezoelectric model adopted.